From reading all of this, I think a toy hauler would be your best bet. In addition to secure storage of several bikes you could also build a small workshop in the back for maintaining bikes. Include the basic tools and a maintenance stand and you would be able to work on your bikes out of the weather. Even with a full size truck, you'd be hard pressed to get 4-6 bikes under a cap and easily accessible. If you had them on some rack system in the truck, you still need to find a way to get to the front of the bed to release whatever mechanism is up there to secure them. Not easy with 6 bikes side-to-side and under a cap. If they were just placed in the back with no rack, you can count on them being a mess with pedals/pegs intertwining with spokes and etc. Just a mess. With a toy hauler, you could probably set up the back to hang a few bikes from the ceiling and secure more to the floor.